Waste collection systems such as sewers, sumps, wet wells, digesters, clarifiers, classifiers, collection tanks, etc. must be cleaned periodically in order to maintain proper fluid flow and capacity. Cleaning removes sand and other deleterious materials that have infiltrated into, for example, a sewer as well as solid materials that have settled out from the normally slow moving waste slurry that varies in volume and flow rate depending on the collective amount of effluents emptied into the waste collection system over time. In order to properly clean large capacity waste collection systems such as collection tanks or the vast lengths of sewer lines in a typical city, an efficient and cost effective method of cleaning must be employed that can handle the large volume of material that must be removed from a typical waste collection system.
Typically, commercial waste cleaning operations utilize a water jet router made up of a high pressure water pump feeding pressurized wash water through a hose having a cleaning head on its end. This cleaning head has water nozzles on its back face which creates a jet action resulting from the high pressure water flowing out the nozzles. The high pressure water jet action both washes the downstream waste collection system such as sewer pipe and propels the cleaning head upstream for continuous washing action of the entire length of the waste collection system such as sewer pipe being cleaned. The position of the cleaning head and its rate of forward travel is regulated by control of the hose reel integrally mounted on the washing truck.
Commercial waste cleaning operations then utilize one or the other of the following two known systems and methods for moving the resulting water slurry produced from the washing action into a collection box, where the solid material is removed and disposed of in a dump or landfill.
First, a second hose may be lowered into a manhole downstream of the cleaning head and is in communication with the resulting water slurry produced from the washing action. This hose is connected to a vacuum system which lifts the water slurry and all contained debris up from the bottom of the manhole into a vacuum holding tank mounted on the rear of the wash truck. Thus, the high pressure wash water brings the solid materials suspended in water to the manhole and the vacuum action picks up the waste material and deposits it into the truck-mounted holding container. When the container becomes full, the materials contained in the container are removed and disposed of, typically in a dump or landfill.
Second, the operation may include a semi-submersible pump to move the water slurry produced by the washing action into the collection box. The submersible pump pushes the slurry up in a column through a slurry hose which is connected to and deposit the slurry into a pressurized collection container located on the surface. Again, when the container becomes full, the materials contained in the container are removed and disposed of, typically in a dump or landfill.
Choosing between the use of a submersible pump to push the waste water slurry into the collection container or use of a vacuum to suck the slurry into the container turns largely on the conditions within the waste water system. If, for example, there is a large volume of liquid relative to solids in the slurry, vacuuming becomes very inefficient and possibly infeasible. A submersible pump, by contrast, requires a large volume of liquid to effectively push the slurry upward into the collection box. If very little liquid is present in the waste water system, a pump will be inefficient or may not work at all, and a vacuum is required.
Existing technologies typically include a truck or other apparatus with a high pressure washer, and either a pump or vacuum for moving the waste water slurry into the collection box. Because field conditions dictate which type of technology is used, though, it is generally necessary to go to the particular waste water system to be cleaned and examine the conditions before choosing an apparatus to perform the work and delivering the apparatus to the jobsite.